fix(presets): use dated Doubao model id and price 6-digit dated models

Volcengine Ark rejects the bare model name doubao-seed-2-1-pro with a 404
("model does not exist or you do not have access to it") even after the
model is activated; the API requires the full dated id
doubao-seed-2-1-pro-260628. Update the Doubao preset model id across all
apps (config default, generated catalog, and OpenClaw namespaced refs).

Pricing lookup only stripped 8-digit (YYYYMMDD) and ISO date suffixes, not
the 6-digit YYMMDD format Volcengine uses (-260628, -250615), so real
Doubao usage never matched the bare-name pricing seed and showed $0 cost.
Extend strip_model_date_suffix to also strip 6-digit YYMMDD (with
month/day validation to avoid eating non-date version suffixes), keeping
the bare-name pricing seed as the canonical identity. This also fixes
pricing for every other Volcengine Doubao model. Add unit and end-to-end
regression tests.

src-tauri/src/codex_config.rs

@@ -2655,7 +2655,7 @@ web_search = "disabled"
             ("gpt-5.5", "https://www.packyapi.com/v1"),
             ("gpt-5-codex", "https://aihubmix.com/v1"),
             (
-                "doubao-seed-2-1-pro",
+                "doubao-seed-2-1-pro-260628",
                 "https://ark.cn-beijing.volces.com/api/v3",
             ),
             ("Pro/moonshotai/Kimi-K2.6", "https://api.siliconflow.cn/v1"),